A substantially amorphous thermoplastic saturated polyester resin (hereinafter referred to as "LPES" for brevity), an ethylene-ethyl acrylate copolymer (hereinafter referred to as "EEA" for brevity) and an ethylene-vinyl acetate copolymer (hereinafter referred to as "EVA" for brevity) are thermoplastic resins having excellent flexibility, rubber elasticity and low temperature characteristics and are widely used as a material to be blended with a wax, a base resin for hot melt adhesives and a molded product.
Hot melt adhesives prepared by mixing EEA or EVA with adhesives such as rosins, turpentine oil, polyisobutylene and paraffin, and waxes do not always have a sufficient adhesive force, and have the disadvantage that an adhesive force at high temperatures is poor. Hot melt adhesive composition comprising a substantially non-crystalline thermoplastic saturated polyester resin alone or a mixture of the substantially non-crystalline thermoplastic saturated polyester resin and an epoxy resin are known. This adhesive has practically acceptable properties such as adhesive properties and flexibility, but in many cases its adhesive force is poor.
Methods for preparing a composition having excellent adhesive properties by compounding a butadiene-acrylonitrile copolymer, polyvinyl acetate, dimeric acid-based polyamide, thermoplastic polyurethane, amorphous thermoplastic polyester and so forth to a thermosetting resin composition containing as a main component polyfunctional cyanate ester compounds which are the component (B) of the present invention are described in, for example, U.S. Pat. Nos. 4,396,745 and 4,404,330, and U.S. Patent Application Ser. No. 711,291, filed on Mar. 13, 1985, now U.S. Pat. No. 4,645,805. However, the object of those methods is to obtain a thermosetting composition containing the component (B) of the present invention as the main component. Although this composition exhibits excellent characteristics, it has the disadvantages that since a curing reaction of the component (B) is essential, a relatively long time is required for heat curing; since the composition is thermosetting, the storage stability over a long period of time is poor; and the cost is expensive.
As a result of extensive investigations on utilization of the unique properties of a cyanato group of a compound having a cyanato group (--O--C.tbd.N), it has been found that the adhesive properties can be greatly improved by adding the compound having a cyanato group to resins for hot melt adhesive such as EVA, EEA and LPES.